Where to put boto3.Session creation in my FastAPI application?

Question

I'm debating between either creating a global boto3.Session for my OpenSearch Python client or creating a new session at the beginning of every endpoint. I can't find documentation anywhere about when Sessions expire or if they expire. Every boto3.Session() call is costing me 50ms-100ms in latency, so it'd be great if I could just create a global one and have it never expire. Any guidance would be greatly appreciated.

Context: I've set up a Load Balanced Web Service on a public subnet to connect to my OpenSearch cluster in a private subnet, both in the same VPC. The Load Balanced Web Service is a FastAPI application.

Answer 1

The boto3.Sessions don't expire unless your credentials do. So, maintaining one global session make absolutely sense.

I'm not sure how you code is structured but you can find a basic example below:

from fastapi import FastAPI
import boto3

app = FastAPI()

session = boto3.Session() # ← global reusable boto3 session

@app.get("/some-endpoint")
def some_endpoint():
    client = session.client('opensearch')
    # ...
    return {"message": "Success"}